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07-24-2007, 04:58 PM #1
I have to drill 20,000 .406 (-.002 +.007)holes in A36 material. The part is .75 thick and it's a thru hole. We have ran this job a couple of times, but the quantities where smaller. All I did was use a spot drill and a 13/32 drill. Drill was just HHS with a feed of 6.4ipm, peck every .150 and 1800rpm. Good enough tool life, about 500 pcs before resharpening. We had to deburr the back side of the part from where the drill broke thru. Operator did this, amongst other things while the machine was running. But there is a lot of other things to deburr, so I'd really like to eliminate this task.
Since it is such a high quantity, I decide to call Allied tool and see what they have in the means of a spade drill with coolant thru and something that could deburr the back side and top. I was hoping not to spot drill and not have to deburr the backside of the part. (save time). We quoted it the same way we had ran it before, but I figured I'd try to improve on the process. I imagine that this will save about 15 or 10 seconds per part. That's a guess. The machine is a mid 90s Leadwell MCV 1000 vertical machining center. I hooked up a coolant inducer that can make it to about 500psi, the specs say 900psi, but it's lying. Since it is a coolant inducer, I use a special 40 taper holder that I can only go from 1.125 down to 5/8 dia tools. Easy enough with a spade drill holder, I'll just get one with .75 shank.
Allied called me back and wants $480 bucks for the custom spade drill holder with a 45 degree chamfer tool on it. Plus 80 bucks for the custom spade drill so I can move off center when I break thru and chamfer the back side of the hole. Sure, when you do the math it's worth it, sounds good. But what happens when the operator forgets to tighten the vise and destroys my $560 drill. That's just a little too steep. I can imagine I talk the boss into this and some kid kills the drill on the second cycle. It's my rearend that gets kicked. Imagine that we break 2 of these drills, that's $1120, but we are still in the profit.....just sounds crazy.
Anybody have any thoughts on this? Maybe a cheaper way to do what I want. I really can't fool proof the work holding, because we don't have automatic vises or anything like that. I can stress to the operator to tighten the vise and double check himself. Maybe another company besides Allied that sells something that can drill and deburr both sides of these holes with the specs that I want. Or just a carbide drill that I can eliminate the spot drilling with, but I still have deburr the backside, which is ok, it's an improvement. Thanks for reading, hope I explained it well enough.
07-24-2007, 05:14 PM #2
Iscar chamdrill will go through that faster than a spade drill without pecking, they have a chamfer ring for the top of the hole that attaches to the drill if you want it, it won't leave much of a burr on the bottom, won't need spot drilling. Your Iscar rep should be able to give you one to test. Prices will be similar to the Allied tool, but Ebay has them for ± $100
You will need to watch insert life so the insert doesn't fail and wipe out the drill body. but that's true of any carbide drill isn't it?
07-24-2007, 05:19 PM #3
These spade drills are one hell of a price.I tend to buy of ebay but it`s still sore to go to AM for spade bits.I used to run higher volumes of holes than that on multispindle lathes (think 40000-70000 holes a week)and through trialling different makes ended up sticking with Guhring stub drills.Normal HSS.Price here was about $50 for ten drills,we did not regrind them just threw them away and found it very cost effective.If you want better than HSS go for HSCO version of the same drill,still cheap.No spotting as the stub drill is very rigid but it still leaves deburring the back of the hole to think about.I would go with a dedicated deburring tool in another holder.Drill all the holes in the part,change tools and deburr.It`s only going to cost a few dollars to try.
07-24-2007, 06:24 PM #4
+1 on the Iscar Chamdrill!
They even have a promo going thru September 28th.
Buy 4 carbide drilling heads and get the drill body for $95.
Total investment $300, and you should get thru all 20,000 holes.
ETA, the more I think about it, you *might* get 5000 holes per insert, but I have only ever had to drill 2K worth with one tip. I bought 2, but only used one. This was in A36.
07-24-2007, 11:28 PM #5
I have not drilled many holes under 13mm in Allied and am not comfortable with the aspect. I doo love Allied tools for bigger holes tho.
I have used Iscar Chamdrilljets in tougher applications and they could run the tougher stuff better as they were carbide tipped. (which Allied also has now - Genesis series...) However - I found the co$t/hole to be the same as between the Allied and the Iscar with the layout (cra$h co$t) to be considerably more for the Iscar, but the Iscar was a bit quicker too. ....
For .406 I would feel warmer/fuzzier going with either the type tip that the Iscar ChamdrillJet or Allied Genesis has than the standard spade.
Any of these will not need a spot drill for anything short of chamfering if you go with the shorter holders. Allied has the add-on type chamfer holders that set-screw on to the regular shanks, but that may be only for the bigger series holders anyhow. ???
I would seriously check into the Screw Machine Length twist drills as was mentioned above. I runa LOT of holes with this type drill with great results. (And I run it dry for my application! - I use Titex A1149TFL series tho.)
A 5/8" 6 flute (chatterless?) 60* (my preferance and nobody is checking anyhow) countesink in a cordles drill will doo the back sides just fine!
Think Snow Eh!
07-24-2007, 11:55 PM #6
I could get ya a YG Spade drill cheap. Probably say 100 for the body plus 30 per tip maybe. You could hire some cutter shop to modify your inserts to cut a back chamfer and you could use the point to deburr the top maybe.
07-25-2007, 08:28 AM #7
Give stellram a call
They just came out with some super whizzy drills called 'hardcore' *
I tried them on my EN24 job... banged 2000 9.4 mm dia holes in 25mm deep in 1 peck,at about 3400 rpm and .18/rev feed (600 mm/min)
The drill still looks good enough for another 1000 holes
*Bet I set everyones porno filters off with that..... but thats what they call 'em
07-25-2007, 09:38 AM #8
I truly agree with the 2 guys that suggested Chamdrills. They are awesome, used them for years. But, you have to push them at the suggested speeds and feeds or they don't work well. When you find the sweet spot, they will run forever. Also, through coolant is a must. Good luck, Paul